Clipping raster image files

Raster Manager lets you perform non-destructive clipping of raster image attachments. Only one raster image at a time can be clipped. With the clip tools, you have the choice of either of two clipping modes:

• Clip Boundary — lets you crop an image to display only the area of interest.

• Clip Mask — lets you clip out a portion of the image. Masking can be used, for example, to clear an area for text display.

In either case, the clipping polygon can be an existing closed element, an existing fence, or you can place a block interactively.

When using the Clip tool from the Raster Manager dialog box (Edit > Clip) you must first select an image or else the Clip menu item is disabled.

When using the Clip tool from the Raster Control tool box, you have the choice of selecting the image before or after selecting the tool. If an image already is selected, prior to selecting the tool, then that image will be clipped. If no image is selected, then you can select the image after selecting the Clip tool.

To crop an image interactively

1. In the Raster Control tool box, select the Clip tool.


2. In the tool settings, set Method to Block and Mode to Clip Boundary.


3. If more than one raster image is attached, identify the image to be clipped.


4. Place a data point to define the first point of the clipping block.


5. Place a second data point to define the opposite corner of the clipping block.


6. Accept to complete the clipping operation.

   Image with clipping block boundary defined (left) and after clipping (right).

To crop an image using an existing fence or closed element

1. Use the Place Fence tool to place a fence defining the clipping boundary for the image.
   or
   Place an element to define the clipping boundary.


2. In the Raster Control tool box, select the Clip tool.


3. In the tool settings, set Method to Fence or Element, as appropriate, and Mode to Clip Boundary.
   Fence is an available option only if a fence is present in the design.


4. If more than one raster image is attached, identify the image to be clipped.


5. Accept the fence as the clipping polygon.
   or
   Identify the element to use as the clipping polygon and accept with a second data point.
   The image is clipped to the shape of the fence or element.

   Image with fence or element defined (left) and after clipping (right).

Using the same procedures as those above, for clipping boundaries, you can mask an area of a raster image. This can be used to place some text describing the image, for example. For these operations, you simply set Mode to Clip Mask, as the following example shows.

To mask part of an image interactively

1. In the Raster Control tool box, select the Clip tool.


2. In the tool settings, set Object to Block and Mode to Clip Mask.


3. If more than one raster image is attached, identify the image to be clipped.


4. Place a data point to define the first point of the clipping block.


5. Place a second data point to define the opposite corner of the clipping block.


6. Accept to complete the clipping operation.


7. (Optional) Repeat steps 4–6 to place additional clipping masks on the raster image.

   Image with clipping block mask defined (left) and after clipping (right).

Modifying clipping polygons

Where you have clipped a raster file previously, you can modify or delete the boundaries of its clipping polygon(s). This may be to display more or less of an image that has been cropped, or to create a larger masked region to add more text. Once you have selected the clipping polygon, you can modify it in a similar fashion to that used for normal elements.

When using the Modify Clip tool from the Raster Manager dialog box (Edit > Modify Clip) you must first select an image or else the Modify Clip menu item is disabled.

When using the Modify Clip tool from the Raster Control tool box, you have the choice of selecting the image before or after selecting the tool. If no image is selected, then you can select the image after selecting the Modify Clip tool.

When you identify the polygon to modify, the identification point defines the way that the polygon is modified. For example, if you identify a vertex, you can move the vertex. Similarly, if you identify a side of a polygon, you can move the side.

To modify a raster clipping polygon with automatic updates

1. In the Raster Control tool box, select the Modify Clip tool.


2. Turn on Update After Each Modification.


3. If more than one raster image is attached, identify the required image.


4. Identify the polygon to modify, at the point at which you want to perform the modification.
   That is, at a vertex if you want to move the vertex, or at a point on a side if you want to move the side.


5. Move the pointer to modify the clipping polygon as required.


6. Enter a data point to complete the modification.
   The image updates to show the new boundaries of the clipping polygon.


7. (Optional) Repeat steps 4–6 for other modifications.

Modifying a side of a clipping polygon (top) and the result (bottom).

Modifying a vertex of a clipping polygon (top) and the result (bottom).

For instances where you want to make a number of changes, or where the raster image is large and takes some time to update, you can turn off automatic updating. This lets you make all the modifications to the clipping polygon, first. You then enter a Reset to update the image.

To modify a raster clipping polygon without automatic updates

1. In the Raster Control tool box, select the Modify Clip tool.


2. Turn off Update After Each Modification.


3. If more than one raster image is attached, identify the required image.


4. Identify the polygon to modify, at the point at which you want to perform the modification.
   That is, at a vertex if you want to move the vertex, or at a point on a side if you want to move the side.


5. Move the pointer to modify the clipping polygon as required.


6. Enter a data point to complete the modification.


7. (Optional) Repeat steps 4–6 for other modifications.


8. Reset to view the results.
   The image updates to show the new boundaries of the clipping polygon.

Deleting clipping polygons

Using the Unclip tool in the Raster Control tool box, you can delete one or more clipping polygons from a raster image. Similarly, you can delete all clipping polygons from a raster image, using Unclip in the Raster Manager dialog box (select Edit > Unclip).

To delete selected clipping polygons from a raster image

1. In the Raster Control tool box, select the Unclip tool.


2. In the tool settings window, set Delete to Selected Polygon.


3. Identify the raster image from which the clipping polygon(s) is to be removed.
   The clipping polygons for the selected raster image are highlighted.


4. Identify a clipping polygon to delete.
   The selected clipping polygon highlights in a different color.


5. Accept to delete the clipping polygon.


6. (Optional) Repeat steps 4 and 5 to remove further clipping polygons from the selected image.